[vlc-devel] [PATCH 4/6] decoder: add decoder_UpdateVideoFrameLatency

[Thomas Guillem]

This function must be used by threaded decoders to notify the frame latency to
the decoder clock.
---
 include/vlc_codec.h | 22 ++++++++++++++++++++++
 src/input/decoder.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/include/vlc_codec.h b/include/vlc_codec.h
index 28a65846d9..6e8b3f7998 100644
--- a/include/vlc_codec.h
+++ b/include/vlc_codec.h
@@ -65,6 +65,7 @@ struct decoder_owner_callbacks
             /* Display rate
              * cf. decoder_GetDisplayRate */
             float       (*get_display_rate)( decoder_t * );
+            int         (*update_frame_latency)( decoder_t *, unsigned frame_count );
         } video;
         struct
         {
@@ -474,6 +475,27 @@ static inline float decoder_GetDisplayRate( decoder_t *dec )
     return dec->cbs->video.get_display_rate( dec );
 }
 
+/**
+ * This function updates the frame latency of the video decoder
+ *
+ * It must be used when using threaded decoders in order to notify a higher
+ * delay to the decoder clock.
+ *
+ * @return 0 in case of success, -1 otherwise. In case of error, the decoder
+ * module should disable threaded decoding or abort.
+ */
+VLC_USED
+static inline int decoder_UpdateVideoFrameLatency(decoder_t *dec,
+                                                  unsigned frame_count)
+{
+    vlc_assert(dec->fmt_in.i_cat == VIDEO_ES && dec->cbs != NULL);
+
+    if (!dec->cbs->video.update_frame_latency)
+        return -1;
+
+    return dec->cbs->video.update_frame_latency(dec, frame_count);
+}
+
 /** @} */
 
 /**
diff --git a/src/input/decoder.c b/src/input/decoder.c
index 57c9de6a1e..609dd82026 100644
--- a/src/input/decoder.c
+++ b/src/input/decoder.c
@@ -741,6 +741,35 @@ static float ModuleThread_GetDisplayRate( decoder_t *p_dec )
     return rate;
 }
 
+static int ModuleThread_UpdateVideoFrameLatency(decoder_t *p_dec, unsigned frame_count)
+{
+    struct decoder_owner *p_owner = dec_get_owner(p_dec);
+    unsigned frame_rate, frame_rate_base;
+
+    if( !p_owner->p_clock )
+        return -1;
+
+    if (p_dec->fmt_out.video.i_frame_rate > 0
+     && p_dec->fmt_out.video.i_frame_rate_base > 0)
+    {
+        frame_rate = p_dec->fmt_out.video.i_frame_rate;
+        frame_rate_base = p_dec->fmt_out.video.i_frame_rate_base;
+    }
+    else if (p_dec->fmt_in.video.i_frame_rate > 0
+          && p_dec->fmt_in.video.i_frame_rate_base > 0)
+    {
+        frame_rate = p_dec->fmt_in.video.i_frame_rate;
+        frame_rate_base = p_dec->fmt_in.video.i_frame_rate_base;
+    }
+    else
+        return -1;
+
+    vlc_tick_t latency_us = VLC_TICK_FROM_SEC(1) * frame_count
+                          * frame_rate_base / frame_rate;
+
+    return vlc_clock_SetDecoderLatency( p_owner->p_clock, latency_us );
+}
+
 /*****************************************************************************
  * Public functions
  *****************************************************************************/
@@ -1707,6 +1736,7 @@ static const struct decoder_owner_callbacks dec_video_cbs =
         .queue_cc = ModuleThread_QueueCc,
         .get_display_date = ModuleThread_GetDisplayDate,
         .get_display_rate = ModuleThread_GetDisplayRate,
+        .update_frame_latency = ModuleThread_UpdateVideoFrameLatency,
     },
     .get_attachments = InputThread_GetInputAttachments,
 };
-- 
2.20.1